Femtocells and small cells reduce total network energy consumption

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Published on Wednesday, 23 November 2011

Written by David Chambers

Climate change is a major concern worldwide today. Perhaps surprisingly, an award winning research study determined that the adoption of femtocells and small cells could reduce energy consumption by up to 70% in urban areas. With mobile networks needing to deliver more and faster data, the energy efficiency of doing so using small cells makes a compelling case.

 

 

Researchers from Alcatel-Lucent's Bell Labs were tasked to investigate the implications of mobile broadband on environmental sustainability. They looked at a variety of aspects, including replacing air travel with video conferencing and telecommuting from home. Although the report was published in 2009, it still makes a valid case for the energy efficiency of a small cell approach.

The telecom industry consumes a small but significant proportion of energy

Telecommunications networks do consume a small but significant percentage of global energy. A typical example given was for Telecom Italia using 1% of all Italian electricity, covering both fixed and mobile services. KPN in the Netherlands is quoted elsewhere also consuming 1%. Many operators are taking action to deal with this, such as consolidating into fewer data centres and using more efficient technology. France Telecom has set itself the goal of reducing power consumption by 20% by 2020. 

Macrocells need a lot of power

The most interesting aspect for me was the comparison of power consumption between large macrocells and small cells. The report quoted a figure from 2007 of 2.7kW per macrocell site which compares with as little as 5W for the latest femtocells. Hundreds of femtocells can be deployed for the same energy footprint. HIgher capacity small cells may use several hundred watts, and still be more energy efficient if deployed in areas of high utilisation.

This equates to a substantial energy bill for the network operator too. In countries where electricity is hard to connect up to, diesel generators may have to be installed on site. The cost of these, including the cost of delivering the fuel to each site, can make energy costs even more significant. For example, in Africa, energy can rise to as much as 75% of total network operating costs.

More energy efficient macrocells

Measures have been taken to deal with this issue of course. The latest basestation products are much more energy efficient that their predecessors. Vendors have added features which reduce power, such as switching off additional carrier capacity overnight, more efficient power supplies and RF power amplifiers. For more remote sites, standalone energy management techniques have been introduced from the likes of Power Oasis.

But small cells still make a more significant difference

The study found that while macrocells would be a more energy efficient solution for voice only networks, total energy savings of up to 70% could be achieved through use of femtocells and small cells. As the industry moves further towards high speed data centric traffic, the case becomes even more compelling.

Relatively small takeup can still make a difference

An operator with 40% market share, 20% of customers with femtocells can still satisfy 80% of total demand from customers. The study found that network operators with lower market share would benefit more through some form of network sharing agreement. The larger proportion of accessible femtocells would deliver higher performance and greater utilization where more customers can access these devices.

Summary

Great strides have been made in reducing the energy footprint of mobile networks in recent years. The continuing growing demand for faster and higher capacity mobile data provides a compelling case for small cell deployment. The reduced impact on climate change combined with reduced energy bills is enticing. This research paper makes a strong case for small cells , particularly to satisfy the thirst for mobile data.

Download the full report here